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Hence the moment of the deflecting couple = nBIA If there are n turns in the coil, the moment of the deflecting couple = n BI l – b These two equal, oppositely directed parallel forces having different lines of action constitute a couple and deflect the coil. This force is normal to the plane of the coil and acts inwards. According to Fleming’s left-hand rule, this force is normal to the plane of the coil and acts outwards.įorce on RS, F = BI (RS) = BI l. PQ = RS = l, length of the coil and PS = QR = b, breadth of the coil. The sides PQ and RS are always perpendicular to the field. Hence the sides QR and SP are always parallel to the field. In a radial magnetic field, the plane of the coil is always parallel to the magnetic field. Learn about Magnetic Field Due to Current Element, Biot-Savart Law Working of Moving Coil Galvanometer

A small plane mirror attached to the suspension wire is used along with a lamp and scale arrangement to measure the deflection of the coil. The hemispherical magnetic poles produce a radial magnetic field in which the plane of the coil is parallel to the magnetic field in all its positions. A soft iron cylinder is placed symmetrically inside the coil. The other end of the spring is connected to a binding screw. The lower end of the coil is connected to a hairspring of phosphor bronze having only a few turns. The coil is suspended between the pole pieces of a horseshoe magnet by a fine phosphor – bronze strip from a movable torsion head. It consists of a rectangular coil of a large number of turns of thinly insulated copper wire wound over a light metallic frame.

The Moving Coil Galvanometer Construction of Moving Coil Galvanometer Hence, the deflection in the coil of a moving coil galvanometer is directly proportional to the current flowing in the coil. Torque acts on a current-carrying coil suspended in the uniform magnetic field. Torque on Current Loop, Magnetic Dipole.

Motion in Combined Electric and Magnetic Field.Magnetic Field Due to a Current Element, Biot-Savart Law.Browse more Topics under Moving Charges And Magnetism It consists of permanent horseshoe magnets, coil, soft iron core, pivoted spring, non-metallic frame, scale, and pointer. Moving coil galvanometer is an electromagnetic device that can measure small values of current.